What are the important roles of fire officer , after the fire and before the fire incident ?

As mentioned in your question, things could be monitored ACTIVELY & REACTIVELY. Care is better than cure. Fire and safety Officer play a vital ACTIVE role to make the arrangements for prevention of fires by making Safe System of Work, adopting permit to work system, identifying all the hazards, identifying all ignition, fuel and oxygen sources and make a risk assessment accordingly, regular inspection of the firefighting systems i.e. Fire extinguishers, fire detectors, sprinklers, PPEs etc, 

And by reactive monitoring ( after any incident) fire and safety officer plays also a very important role by making the control measures to control the recurrence of any unwanted event. That is possible by good incident investigation accordingly review all safe system of procedures.

As the role of safety officer is to keep update all the safety equipments update such as(DCP,Co2,Foam,water Fire extinguisher) and further detectors heat,smoke,flash detectors and their panel and fire fighting pump this all responsibility is for safety officer to keep update. and after the fire first of all have to get together all the peoples at assembly point to keep safe life of peoples. and for extinguishing fire the area should be such designed automatically and manually both. Automatically like hydrant system but before starting it must be sure that electric power has been cut of. and manually like this that fire extinguisher and hose reels can be used. and should investigate the fire accident to keep safe the company for further incident. to keep safe from any kind of incident the working area should be complete without risk like no wires should be nude,and  all area should be checked on daily by taking round and employees must be trained for safety evaluation plan and trained for using fire fighting equipments by giving them training monthly.

I believe80% accident, incident or fire can be prevented & control prior to happen, if carried out (a) risk assessment (b) put appropriate preventive & precautionary measure in place (c) provide training & maintenance (d) timely financial support (d) under one & independent organization (e) who knows ERTL and can give decision during emergency as final; otherwise person has to be faced unexpected extinguishment & consequences. The resultant will be horrible & costly followed by loosing job or even jail.

keep all the fir equipment and fire tenders ready for any emergency..regular and vigorous training of the fir fighters.timely management and repair of the fire equipment.